1. Field of the Invention
The present invention relates to a light emitting diode (LED), and more particular to a light emitting diode package structure and a method of manufacturing the same.
2. Description of Prior Art
A light emitting diode (LED) is a solid-state semiconductor device that combines two carriers produced by passing an electric current through the LED to release energy in the form of light. LED has the advantages of a compact size, a fast response rate, and a pollution-free feature, so that the LEDs can be used extensively in different industries. Since LEDs have bottlenecks including an insufficient brightness and a low luminous efficiency at an early stage, a high power LED is developed later to overcome the drawback of insufficient brightness, and thus LEDs become increasingly popular in the high power illumination market and tend to gradually take over the position of traditional tungsten lamps. LED products have the potential of replacing traditional illumination devices.
As LED manufacturing technologies are improved constantly and new materials are developed to meet the requirements of various different applications, the technology and structure of LEDs become mature, and thus leading to the development of a high power LED with enhanced energy capacity and brightness as well as the extensive use of high power LEDs in different areas. Among the types of high power LEDs, the surface mount device light emitting diode (SMD LED) is a common type of LEDs, and the general SMD LEDs are divided mainly into two types: a lead frame type and a printed circuit board type. The lead frame type uses a metal frame and a heat-resisting plastic material to produce a socket as a fixed lead frame of an LED chip by injection molding, and the printed circuit board type uses a composite material as a substrate, and both of these two types have to go through the processes of die bonding, wire bonding and encapsulation processes to complete the LED structure.
In a general die bonding process as shown in FIG. 1, a plastic shell 101 made of an insulating heat-resistant plastic material such as epoxy resin is covered onto an LED chip 102, and a packaging plastic material 103 such as soft silicone is injected into the plastic shell 101. Such arrangement not only prevents moisture or air from being permeated into the packaging plastic material during a non-airtight packaging process of the traditional packaging process, but also uses the plastic shell 101 for receiving the injected packaging plastic material 103 to form a fixed shape of the plastic shell 101, and thus the LED chip 102 can maximize its spectrum effect by the packaging plastic material 103 and the plastic shell 101.
However, there is a major drawback of the aforementioned packaging process, since the package structure and material cannot resist high temperature, and particularly the light emitting diode and other circuit board have to be processed in a soldering pot (at 250° C.˜300° C.), and the plastic shell 101 and the soft plastic material 103 usually cannot stand the high temperature of the soldering pot, and the light emitting diode structure may have broken lines or the plastic shell 101 may become soft. Even if the plastic shell 101 and the soft plastic material 103 can resist the high temperature, the coefficients of thermal expansion of the plastic shell 101 and the soft plastic material 103 are different, and cracks may be produced between the packaging plastic shell 101 and the soft plastic material 103, and thus resulting a defective light emitting diode. To reduce the defects in a manufacturing process, the soldering is conducted manually, and thus making the manufacture more difficult and time-consuming.